The Zee Stem, a cherry interstem on top of Mazzard rootstock, allows a wider range of rootstocks to be used in California cherry plantings.
Getting cherry trees to grow in California is the easy part. It’s keeping them from getting too big that concerns most growers in the San Joaquin Valley.
"Trees in California are going to grow," said Steve Blizzard, farming director at Lagomarsino Farms in Tulare, California. "If you’re not careful, they will double in size."
The limiting factor in growing cherries in the southern San Joaquin Valley is heat and doubling, he said. "We don’t have a whole lot of varieties that do good here. Some use overhead cooling to make the trees think that they’re further north. A lot of things we do because we have to do them, not because we want to."
Lagomarsino Farms is a third-generation family farm growing Brooks, Tulare, and Rainier cherries, grapes, and blueberries. Ag Source, Inc., the farm management arm of Lagomarsinos, provides farm management services and farm labor contracting.
During a tour for members of the International Fruit Tree Association in February, Blizzard said that the company works to be on the cutting edge of trends and technology.
In the field
For example, they planted a new, 30-acre cherry block in January using the Zee Stem cherry interstem patented by Zaiger Genetics, Inc. The interstems were on Mazzard rootstocks and were grafted with Tulare, Rainier, Brooks, and Coral Champagne in the field in March. Blizzard said they were unable to get the varieties they wanted on the interstem, so they chose to graft. "It’s not always mecca when you graft in the field," Blizzard said. "Some call it child abuse."
The interstem, developed for cherries only, is an interspecific cross between peach and almond rootstocks. It allows cherries to be planted on a wider range of rootstocks in California, including Mazzard. Blizzard said that they are one of the first to use the interstem on Mazzard. The interstem is supposed to improve precocity and encourage a spreading habit in the tree.
They’ve spaced the new planting 20 feet between rows in a 16-foot diamond pattern. In older cherry plantings, spacing is 16 by 16 feet. "We’re not buying into the idea that the interstem is that much more dwarfing," he said. "Until we know exactly what the Zee Stem will do, we’re going to stay a little wider in our plantings."
Blizzard said that their goal is to push the trees hard the first two years to fill in their space and then settle them down. They try to get the trees to develop leaf cover early because they are concerned about sunburn. Though some limbs are tied to the ground, much of the training is done by twisting and breaking limbs to get downward angles. Trees are mechanically topped at 12 feet to eliminate the need for ladders taller than 10 feet.
Dormex, a rest-breaking agent that improves bloom uniformity, is used on some of their cherry acreage.
They aim for 10- to 10.5-row size fruit, which means that they have to reduce the crop load substantially, he said, adding that growing 12-row cherries doesn’t do any good. Most of their thinning is done by pruning.
Blizzard said they are not using orchard systems adaptable to mechanization—yet. "Company policy is to do things that lend to automation. Right now, we don’t see anything that’s close to being adopted for these three cherry varieties. But when something looks promising, we’ll be some of the first on it."
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